AI performance hit

Hello simracers. I've been trying to get into AC lately and found out that a grid of 20 cars makes my race a slideshow, while I have 80+ fps while hotlapping. Considering there are better AI in simracing at the moment which are much less fps consuming, what makes the wip AI of AC so fps hungry? Are there any tweaks, or what settings do I have to turn down in order to get at least 50fps? I have forced 8xAA, shadows on med, world detail on max, reflections on low already.

Just in comparison R3E with a 24 grid runs for me probably at 60 because I can't feel any latency, rFactor 2 used to be laggy but now I can run a 30 grid around 24h Nords with 50-60 fps at the start of the race.

My specs: AMD Phenom II X4 (which I know is the weakest part of my PC, I'm not planning an upgrade any time soon if you wanted to give me that advice), AMD Radeon R9 270X, 8GB RAM, everything else is irrelevant...

AC's AI uses the same physics as the player, hence why it is very heavy on the CPU, even heavier than online.

In addition to this, AC's CPU/GPU distribution can still use some optimalisation. Kunos has tweeted that update 1.1 will contain some of these optimalisations. I'm sure there will be more updates coming in this respect as time goes on.

Summarasing: your CPU will be the bottleneck with a lot of AI, and turning down the graphics is unlikely to help.